It is important to be on the same page when talking about the game with other members of the league and--more importantly--your team members. This is an overview of the most important and basic terms of the game.
Note: flag football rules can be found here.
Backfield: The area behind the line of scrimmage.
Ball carrier: Any player who has possession of the ball.
Blitz: A play where the defensive team sends players rushing towards the line of scrimmage as soon as the ball is snapped to try to sack the quarterback.
Blocking: The act of preventing a defensive player from getting to the ball carrier; blockers use their arms and bodies but may not hold an opponent.
Bomb: A long pass thrown to a receiver sprinting down the field.
Bump-and-run: A technique used by pass defenders, where they hit a receiver once within 5 yards (1 yard in college) of the line of scrimmage to slow him down, and then follow him to prevent him from catching a pass.
Button hook: A pass route in which the receiver heads downfield, then quickly turns back toward the line of scrimmage.
Clipping: Blocking an opponent below the waist from behind; this illegal block is a personal foul, punishable by a 10-yard penalty.
Cover or coverage: Preventing a player from gaining yards; in pass coverage, a defender follows a receiver to prevent him from catching a pass; in kick coverage, members of the kicking team try to prevent a long kick return.
Cut back: A sudden change in direction taken by a to make it more difficult for defenders to follow and tackle him.
Dead ball: A ball becomes dead when a play is over and becomes live as soon as it is snapped for the next play.
Defensive back (DB): A member of the defensive secondary. Defensive backs generally try to keep receivers from making catches. Safeties, cornerbacks, nickel backs, and dime backs are considered to be defensive backs.
Down: One of 4 chances a team on offense has to gain 10 yards; also, the state of a player who has just been tackled; also, a ball that a player touches to the ground in the end zone to get a touchback.
Down & In: A pass pattern where the receiver runs straight downfield, then suddenly cuts toward the middle of the field.
Down & Out: A pass pattern where the receiver runs straight downfield, then suddenly cuts toward the sideline.
Drive: The series of plays a team puts together in an attempt to score.
Encroachment: If a player (besides the center) is in the neutral zone and contact occurs prior to the snap; a foul punishable by a 5-yard penalty.
End zone: The area between the end line and goal line bounded by the sidelines, which a team on offense tries to enter to score a touchdown.
Fair catch: When a kick returner decides only to catch a punt or kickoff and not advance it, protecting himself from being hit by an opponent; he signals for a fair catch by raising one hand in the air and waving it.
First down: The first chance out of 4 that a team on offense has to advance 10 yards down the field; as soon as it gains those yards, it earns a new first down.
Forward pass: A pass thrown by a team closer to the opponent’s goal line; a team is allowed to throw only one forward pass per play, and it must be thrown from behind the team’s line of scrimmage.
Foul: a violation of football’s rules by a team or player, punishable by a penalty.
Fumble: when a ball carrier loses possession by dropping the ball or having it knocked away before a play ends; the first player to regain possession of the loose ball is said to make the recovery, and his team becomes the offense.
Goal line: a line drawn across the width of the field, 10 yards inside each end line, which a team must cross with the ball to score a touchdown.
Holding: a foul where a player impedes the movement of an opponent by grasping or hooking any part of his body or uniform; punishable by a penalty — 10 yards if against the offense, 5 yards (10 yards in college) plus a first down if against the defense.
Interception: a pass caught in the air (picked off) by a defender whose team immediately gains possession of the ball and becomes the offense.
Line of scrimmage: an imaginary line which no player may cross before the snap; each team has its own line of scrimmage, separated by the neutral zone.
Lineman: a player who starts each play within 1 yard of his line of scrimmage.
Man-in-motion: a single player on the offense who is permitted to move prior to the snap; he may only run parallel to the line of scrimmage or away from it.
Man-to-man defense: Pass coverage in which every defensive back is assigned to a particular receiver.
Neutral zone: the region that contains the ball as it sits on the ground before each play; the area between the two lines of scrimmage.
Offside: when any part of a player’s body is beyond his line of scrimmage when the ball is snapped; a foul punishable by a 5-yard penalty.
Pass patterns or pass routes: pre-determined paths receivers follow to help the passer quickly locate them so he can more easily get them the ball.
Pass protection: blocking by offensive players to keep defenders away from the quarterback on passing plays.
Pass rush: a surge by defenders to get past blockers and sack the quarterback.
Picked off: intercepted.
Pocket: the area behind the offensive line, where the quarterback is protected by his blockers.
Point-after-touchdown (PAT): After a touchdown, a team has one play to score one point by getting back into the endzone from five yards, or scoring two points by getting the ball into the endzone from 10 yards.
Possession: to be holding or in control of the football.
Punt: when a player kicks the ball before it hits the ground; an opponent tries to catch and advance it the other way.
Quarterback: the leader of a team’s offense, he takes the snap from the center and either hands the ball to a running back to run with, passes it to a receiver or runs with it himself; he also communicates each play to his teammates.
Receiver: an offensive player who catches or attempts to catch a forward pass.
Rush: a running play; also, a pass rush.
Sack: a tackle of the quarterback behind his line of scrimmage.
Safety: when a ball carrier is tackled in his own end zone after bringing the ball there under his own power; the defense earns 2 points and receives a free kick from the offense’s own 20-yard line.
Scrambling: evasive movements by a quarterback to avoid being sacked.
Series: the group of 4 downs a team has to advance 10 yards.
Sideline: the boundary line that runs the length of the field along each side; a ball carrier or ball that touches or crosses the sideline is out of bounds.
Slant: A play in which the ball carrier runs across the field at an angle instead of running straight toward the end zone.
Snap: when the center while facing forward quickly hands the ball between his legs to a player standing behind him (usually the quarterback) to start each play.
Stiff arm (or straight arm): an illegal push by a ball carrier to ward off a tackler.
Touchback: when a player who gains possession of a ball in his own end zone kneels to the ground and automatically starts the next play at his own 20-yard line; also awarded if his opponent kicks the ball across the end line.
Zone defense: Coverage in which the secondary and linebackers drop away from the line of scrimmage into specific areas (zones) when defending a pass play.